Faults are key components in defining fluid migration pathways and seals in sedimentary basins. The sealing capacity of faults is closely related to the petrophysical and geomechanical properties of fault gouge. Clay smear, cataclasis, and diagenesis favor a high capillary breakthrough pressure and low permeability in clastic sediments, and therefore fault gouge seal. However, significant uncertainty remains in accurately predicting the sealing capacity of faults for CO₂ storage. We conducted a series of experiments, including absolute permeability, breakthrough pressure, and post-breakthrough CO₂ permeability measurements on synthetic fault gouge samples, made from homogeneous mixtures of Frio sand and Anahuac shale, lithofacies of tertiary sediments in the Gulf of Mexico basin. The results show that the permeability of synthetic fault gouge decreases by about one order of magnitude with increments of 10 wt% of clay (mostly smectite) from the Anahuac shale. Independent of clay content and bulk porosity, all permeability measurements scale with the void ratio of the clay fraction. The breakthrough pressure of synthetic fault gouge increases by approximately half order of magnitude with increments of 10 wt% clay. The samples with clay content above 40 wt% reach a breakthrough pressure equivalent to a (supercritical) CO₂ column height of more than 100 m. The measurements on fault gouge properties are meaningful to quantitatively evaluate fault sealing capability and migration of buoyant fluids through faults in sand-shale sequences.

断层是定义沉积盆地中流体运移路径和封闭的关键组成部分。断层的封闭能力与断层泥的岩石物理力学特性密切相关。粘土涂片，分解和成岩作用有利于高的毛细渗透压力和碎屑沉积物中的低渗透性，因此有利于断层断层的封闭。但是，在准确预测CO ₂储存断层的封闭能力方面仍然存在很大的不确定性。我们进行了一系列实验，包括绝对渗透率，突破压力和突破后的CO ₂由Frio砂和Anahuac页岩的均质混合物制成的合成断层泥样品的渗透率测量值，墨西哥湾盆地的第三纪沉积物岩相。结果表明，随着Anahuac页岩中粘土（主要是蒙脱石）含量的增加，合成断层泥的渗透率降低了约一个数量级。与粘土含量和整体孔隙率无关，所有渗透率测量均随粘土级分的空隙率而变化。合成断层泥的突破压力随粘土含量的10 wt％的增加而增加大约一半数量级。粘土含量超过40 wt％的样品达到的突破压力等于（超临界）CO ₂立柱高度超过100 m。断层泥性质的测量对于定量评估断层封闭能力和通过页岩页岩层中的断层的浮力流体的迁移是有意义的。